The flight controls of aircraft, and in particular of helicopters, are incorporating more and more electrical actuators, such as for example an electrohydraulic actuator for controlling the pitch of the blades of a rotor. A device for controlling such an electrohydraulic actuator conventionally comprises calculation means incorporating a control electronic card and a monitoring electronic card. The control electronic card transforms instructions from the pilot into an electrical setpoint that is sent via a wired control circuit to the actuator. The electrical setpoint results in the rod of the actuator being extended or retracted by a determined amount. The monitoring electronic card is connected by a wired monitoring circuit to a sensor for sensing movement of the actuator rod. On the basis of information from the control card and from the monitoring card, the calculation means set up a servocontrol loop in order to ensure proper operation of the command. Aviation safety standards require the use of resources that are distinct for processing information from the command card and for processing information from the monitoring card. Those requirements lead to making use of calculation means having two channels. A first channel processes information coming from and going to the control card, and the second channel processes information coming from and going to the monitoring card. This reduces the criticality of a failure of one of the two cards or of one of the two channels. Specifically, failure of one of the control elements (circuit or card) will be detected by the monitoring card, and failure of one of the elements of the monitoring circuit does not lead to loss of control of the actuator.
In order to make equipment compact, a control card frequently takes charge of controlling a plurality of actuators. Such a card generally has a plurality of processors, each connected to a respective control circuit that is dedicated to one respective actuator. Monitoring cards also comprise a plurality of processors, each connected to a respective monitoring circuit dedicated to one respective actuator.
Control devices having such a monitoring and control architecture are found to be reliable, but they represent a large amount of investment in terms of developing, fabricating, and maintaining each of their elements. The accumulated times for developing and fabricating each of the cards require expensive solutions to be deployed in order to satisfy the requirements of aircraft manufacturers for reactivity.